1. Field
Aspects of the present invention relate to an organic light emitting diode (OLED) display and a power supply of the same. More particularly, aspects of the present invention relate to a power supply powering electroluminescence (EL) and an organic light emitting diode (OLED) display including the same.
2. Description of the Related Art
Currently, various flat panel displays having a reduced weight and volume have been developed. Types of the flat panel display include a liquid crystal display (LCD), a field emission display, a plasma display panel (PDP), and an organic light emitting diode (OLED) display. Among the flat panel displays, the OLED display displays an image by using light generated by an OLED by recombination of electrons and holes. The OLED display has gained attention because it has a rapid response speed, has low power consumption, has luminous efficiency, and luminance and a viewing angle which are excellent.
A type of OLED display is classified as a passive matrix OLED (PMOLED) and an active matrix OLED (AMOLED) according to a driving method of the OLED. Among the types, in views of resolution, contrast, and operational speed, the AMOLED that is selectively turned on with respect to every unit pixel is mainly used.
As a power source of the AMOLED, various power sources such as a power source powering EL and a power source powering computation, or logic and powering a system are required. Among them, a capacity of the power source powering the EL is largest. Particularly, the EL power source of a large capacity to generate light energy is required in a television (TV) having the AMOLED of a large size.
FIG. 1 is a block diagram showing an EL power supply according to a conventional organic light emitting diode (OLED) display. Referring to FIG. 1, an EL power supply of the conventional OLED display includes a +ELVDD power source circuit 10 and a −ELVSS power source circuit 20. The +ELVDD power source circuit 10 generates a +ELVDD voltage of the ELVDD power supply supplied to a pixel PX of the OLED display. The −ELVSS power source circuit 20 generates a −ELVSS voltage of the ELVSS power supply supplied to the pixel PX of the OLED display.
A DC power source of the external power supply is applied as an input voltages +Vin of both the +ELVDD power source circuit 10 and the −ELVSS power source circuit 20. A current flowing to the input voltage +Vin of the +ELVDD power source circuit 10 and the −ELVSS power source circuit 20 passes through the +ELVDD power source circuit 10 and the −ELVSS power source circuit 20 and the +ELVDD power source circuit 10 and the −ELVSS power source circuit 20 are grounded.
The +ELVDD power source circuit 10 generates the +ELVDD voltage, which is referenced to the ground (GND) voltage, from the current flowing in the input voltage +Vin. The −ELVSS power source circuit 20 generates the −ELVSS voltage, which is referenced to the ground (GND) voltage, from the current flowing in the input voltage +Vin. The +ELVDD power source circuit 10 and the −ELVSS power source circuit 20 respectively generate the +ELVDD voltage and the −ELVSS voltage by using a transformer.
The +ELVDD voltage and the −ELVSS voltage, respectively generated in the +ELVDD power source circuit 10 and the −ELVSS power source circuit 20, are used to illuminate the pixels PX included in the OLED display. However, the −ELVSS power source circuit 20 has low converting efficiency compared with the +ELVDD power source circuit 10, and a cost of the OLED display is increased to additionally use the +ELVDD power source circuit 10 and the −ELVSS power source circuit 20.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.